Miss Stress-aholic

To my dismay, the last lazy days of summer slowly slipped through my fingers like sand. Before I knew it I was shoved into middle school, where everything was new, loud, busy, and chaotic.
I tried desperately in my spare time to scratch together a story worth writing about, but began thinking negatively- balling up whatever I wrote or tearing it up. Not only that, my whole family was on edge. My mom, my dad, my brother... and especially my sister.
Every day after I returned from school with my siblings, my sister would start a screaming match with my mom about the smallest things- like forgetting to tell her about her violin lesson, or simply not shutting the garage door. It left every one in a bad temper for the rest of the evening, btt before long we began to think that maybe this wasn't so usual.
Every evening my sister stayed up past 11 pm working on homework. She stressed out about it, screamed about it, and blamed all the world's problems on the teachers. She would rant and rave about the national government recommended amount of homework, and how the teachers were horrible people that were out to get us. Worst of all, none of her behavior made any sense. She had the same high-potiential classes as my brother and I, so why weren't we swamped until 11 pm? We soon figured out why.
Every time a teacher assigned a small assignment- like asking us to get the weather predictions for the next 3 days, my sister would go overboard. She would make massive powerpoints, wall-size posters, and creations that took literally days to make. Once she made a poster for her orchestra teacher (extra credit only) on the "circle of fifths." The poster was over twenty feet tall and it cost over $100 in printer ink! It took her days to color everything and to write the Circle of Fifths in huge, fancy scripts. I was horrified. What's more, she demanded all the teachers give her extra credit for her efforts- whether they wanted to or not. Soon she had completely forgotten how to have a life outside of the 6th grade classroom. All she ever did was schoolwork. She made our lives miserable as she ranted about one thing or another, and soon she had created an ego for herself, a reputation, where she had to be the all-knowing genius.
My sister would sit up stiff as a board in her chair, nodding her head enthusiastically whenever a teacher spoke (which looked rather insane), and crinkling her brow and muttering "oh yes, yes, I see." to herself. She acted as if all eyes were always on her. Soon other kids in the school started assuming all three of us were genuiuses and would drop phrases like, "Wow, I aced this test- I probably did almost as well as the triplets" or, "I wonder if any of the teachers know anything about quantum physics.... the triplets would know."
Unfortunately, of all my tales, this is not one that can end with a happy moral. It has none. My sister has grown a little bit less odd when it comes to self-consciousness (no more head nodding), but she still continues to be 1st place know-it-all. I can't say one thing without her trying to correct me and she can't stand to ever be wrong. Not only that, she spends most of her time on wikipedia, looking up random trivia (you could ask about something very random- like, say, an Okapi, and she would be able to give you 10 random facts on it). All I can say is, though this started in 6th grade, it just continues. She takes out all her stress and anger on her family and all I can say is, I hope she survives high school (literally). I just don't know how this can go on!